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. zeno of elea, who predated aristotle, wrote a series of paradoxes that still give us pause today. one of the best known tells the story of achilles and the tortoise and their race. achilles is such a fast runner, he gives the tortoise a head start. they each run at constant speeds: achilles very fast, the tortoise very slow. after a finite amount of time, achilles gets to where the tortoise started, but the tortoise will have moved on. it takes achilles a finite amount of time to get to the tortoise's next spot, but by the time he arrives, the tortoise will have moved on from there as well. and so on, and so on, over and over again, ad infinitum. despite what our senses tell us, zeno is telling us that achilles will never catch the tortoise. zeno's paradoxes were a big problem for the greek philosophers, and they did just about everything they could to avoid confronting the infinite because they based their arithmetic and their entire worldview on something much more tangible: geometry. their notion of the mathematical and the physical was intimately linked to the practice of measurin
in the air. i mean, the air is around us, right? okay? it leaves behind a hole in the air. aha, but wait a minute, the scholars said, "you can't have a hole in the air, because nature abhors a vacuum." so that vacuum gonna be filled up by the air. so you're gonna squeeze down in back and squeeze it right along. and so there's the force. the air squeezes it along. saturday night when you're taking your bath, try ivory soap, the kind that floats. and you sit in the bathtub and there is a soap right there and you go to grab it. you've done it before and you go, "oh, i have it" it keeps going away from you, right? [laughter] you squeeze it right through the water. well, it was thought that cannonballs were squeezed similarly through the air and arrows too. what do you guys think about that? not too many people were satisfied with that, but that's the best they could do at the time. there gotta be some explanation. what's a better one? and along came an italian type by the name of galileo who turned it all upside down. everyone's looking for the force responsible for the motion, galileo said,
okay, let's begin. it used to be thought that the earthth was at rest and the stars went around us. and how could you tell whether or not the earth is at rest and the stars are going around us, or the stars are maybe at rest, we're going around them? in fact, what's the nearest star? begins with an s. you are now-- let me tell you. begins with a s, ends with a n, got a u in the middle, try it. sun. sun. very good, okay. that's the sun. the sun is the nearest star, okay? and we go around, around, around the sun, is that true? but it was one time thought that's not the case. and one of the arguments that was advanced to show that the earth really is at rest and not the other way around is the following: consider a bird at the top of a tree, and down below there's a juicy worm just coming up to the ground. and the bird is up at the top and looks down and sees the worm. now, we know from experience that's its possible for that bird to drop from the tree, come down, catch the worm and fly back up. true? and it was stated as such. it was calculated how fast the world would have to be mov
Search Results 0 to 3 of about 4 (some duplicates have been removed)